Rails app sending mail problem

I have an open source rails project that I’ve gotten up and running under my Dreamhost account as an evaluation for a client of mine. For the most part, the app is running fine until it gets to a part where it needs to send out an email.

According to the logs with debug logging turned on, the email gets generated successfully, but something happens, I think, in the deliver method of ActionMailer and I end up with this error:

NoMethodError (undefined method `path' for nil:NilClass): app/controllers/projects_controller.rb:46:in `send_mail'

Line 46 of projects_controller is:

From my research, everything up to the final “.deliver” is working ok and all the parameters are valid. ProjectsMailer is a fairly simple subclass of ActionMailer.

Does anyone have any ideas where I might look for this? I’m not a rails developer so I’m at a bit of a disadvantage here. Could it have something to do with the core Ruby code not finding the mail program?